


Dirty Little Secret

by assbuttintheimpala



Category: Supernatural
Genre: Age Difference, Alpha Dean, Alpha/Beta/Omega Dynamics, Alternate Universe - High School, Barebacking, Bottom Castiel, Dirty Talk, Lactation Kink, M/M, Male Lactation, Mpreg, Natural Lubrication, Older Castiel, Omega Castiel, Semi-Public Sex, Size Kink, Student Dean, Teacher Castiel, Teacher-Student Relationship, Top Dean, Younger Dean
Language: English
Status: In-Progress
Published: 2016-02-08
Updated: 2016-02-08
Packaged: 2018-05-19 00:47:56
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 2,883
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5949889
Author URL: https://archiveofourown.org/users/assbuttintheimpala/pseuds/assbuttintheimpala
Summary: <blockquote class="userstuff">
              <p>SPN Kink-Meme Prompt : A switch on the normal teacher student mpreg thing. I'd love to see a 12-14 year old Dean knocking up his teacher Cas. Repeatedly if possible. They both really get off on it even though they're keeping the fact that Dean is the one breeding him a secret although maybe some have an idea. Multiples welcome. Lactation / breast growth a plus.</p>
            </blockquote>





	Dirty Little Secret

**Author's Note:**

> This has literally taken forever to write and it's only part 1. Part 2 will be up once I find time to finish it. I have a busy couple of weeks so it may not be up for a little while but I promise it will be finished!
> 
> Original SPN Kink-Meme post [here](http://spnkink-meme.livejournal.com/106475.html?thread=40144875#t40144875)

It was never meant to go as far as it did. They were never meant to be serious but somewhere along the way, the lines were blurred and Castiel wound up pregnant. His belly was huge, his breasts growing larger and more sensitive by the day, his back constantly aching and his feet were swollen and barely fit his shoes anymore. To make matters worse, Castiel was on his own with his family abandoning him as soon as they heard he was knocked up without a mate. If they knew the truth, they would have done more than abandoned him.

Dean Winchester was everything Castiel wanted and couldn’t have. He had sauntered into Castiel’s life with his charming good looks, his strong alpha demeanour and his smooth words which had Castiel’s resolve breaking each and every time Dean would wander into his classroom.

The first time Dean walked in to Castiel’s classroom it was the first day of a new year and while he was writing on the lesson plan on the board, Castiel was hit with the strong scent of Alpha pheromones. At first he thought it was from one of the boys trying out the fake Alpha colognes one could buy but as he inhaled deeper, he noticed it didn’t smell like fake scents which were usually overpowering and unpleasant to smell. He could feel himself react almost immediately, his knees wobbling, heart racing, ass clenching. Frozen in place in front of the white board, Castiel looked towards the door only to see the back of an eighth grader’s head as he moved down the aisle between desks. He watched mouth agape and nostrils flaring to savour the delicious scent as the boy moved all the way to the back of the room and took a seat. As if he had noticed Castiel’s reaction, he looked up only to deliver a lop-sided smirk and a cheeky wink at his teacher.

At the first indication Castiel was getting slick, he told his students to write an essay on what they had done over their summer break before he excused himself. After several minutes in the teacher’s restroom, he managed to calm himself down enough to make his way back to class. With all the other students between him and the enticing Alpha’s scent, Castiel managed to get through the rest of the lesson without further incident. However, Dean’s knowing glances and provocative actions with his pen didn’t help the situation. After that first day, Castiel made sure to bring an extra pair of pants and underwear with him to work.

It was six weeks later that anything actually happened.

Castiel had been stupid enough to give a pop test to all his classes on the same day and then promised them he would have their results back to them by the end of the week. Fortunately, as it was only a 40 minute test, it only took a half hour per test to mark. With the amount of students he taught, it did mean he had to take some of them home with him to finish his marking.

He was up to his last class, his eighth graders, and was getting through them quite quickly as apparently this class didn’t put in a lot of effort. It was as he reached the end of the pile that he became aware of a scent coming from one of the papers. He would know that earthy, pine scent anywhere and before he knew it, he could feel his body reacting to it. Sure enough, there at the bottom of his small pile was Dean Winchester’s paper that reeked of the young Alpha.

The Omega gnawed on his lower lip in indecision before deciding to hell with it and pressed the paper to his face and inhaled the delicious scent. With the rest of the papers abandoned on the floor, Castiel pushed his hand down his slacks and started to play with his slickening hole. He teased himself at first, just rubbing the tip of his finger over his sensitive rim before pressing just the tip inside. He groaned loudly before he inhaled deeper to try gather as much of the scent as he could. His arousal took over in no time, and he soon had two fingers deep inside him, fucking in and out of his hole.

In frustration of not being able to get his fingers as deep as he wanted them, Castiel rid himself of his slacks and underwear. Bare assed on his couch, he resumed his fingering, slipping a third in with the other two, feeling his slick drip down his wrist and onto the fabric below. He was moaning uncontrollably as he found his prostate, rubbing over it insistently feeling the pressure in his gut build and build. His small Omega cock was leaking pre-cum all over his shirt leaving a damp spot that would probably stain but he was too caught up in the three fingers inside him, imagining the young Alpha using him instead, telling him how good he was for him. He imagined Dean doing to him exactly what Castiel was doing, fingering him while letting the Omega inhale his scent until he came. It had the Omega pushing his hips down harder, more and more slick dripping from his ass until finally, he couldn’t hold back any longer and he came hard, his ass clenching and unclenching, searching for that knot to lock him together with his Alpha. Cum spurted from his cock, up his torso all the way to his chin while slick squirted from his ass, coating the couch in a huge wet spot that he would have to clean up straight away if he didn’t want to have to buy a new one.

It was as he got his wits about him that he realised the test paper had drops of his cum on it from how hard he had come. He tried his best to clean it up as well as his couch and sat down to finish his marking trying his best to ignore the fact that he had just masturbated to the thoughts of his underage student. It was after midnight by the time he got into bed but after his intense orgasm, he fell into a deep sleep quite easily.

When Cas awoke the next morning he had a dazed smile on his face as he slowly woke up. As he came back to himself and realised that it was Friday and he had to go to work, he quickly looked at his alarm clock. His stomach dropped as he saw that it was almost 8. He was supposed to be teaching in half an hour and it was a twenty minute drive to school. He cursed himself for sleeping through his alarm as he ran around like a headless chicken trying to get ready. He knew he wouldn't have time for breakfast and instead had the quickest shower of his life before pulling on his clothes while his skin was still wet. The fabric stuck to his skin uncomfortably but he didn't have the time to dwell on it as he moved through his apartment gathering all the papers he'd marked. 

After speeding through the back roads, Castiel made it to school with 5 minutes to spare before the first bell rang. His hair was still dripping water on his shoulders when he walked into his classroom and started to write the lesson plan on the board. Luckily for him, they were only going over their test results before independent reading of the next few chapters of the book. 

His 10th graders were his first class and there were a few chuckles and playful remarks about his unruly state but they were a good bunch of students and let it go once they settled into the lesson. By the end of first period, Castiel felt a lot less frazzled. As he went to write the new lesson plan on the board for his next class, his stomach flipped as he realised it was Dean's class. Remembering what he had done the night before and why he was late that morning had Castiel ducking his head in shame and guilt running through him. It was bad enough that he had gotten off to the thoughts of an underage Alpha but said Alpha was also his student making it that much worse. 

By the time the eighth graders walked into the classroom, Castiel had managed to work himself up into a panic. He tried to hide it as best as he could, smiling and greeting his students by name as they filed inside. Of course, last was Dean Winchester, the perfect specimen of Alpha that had Castiel becoming embarrassingly hard just from the sight of him. He smirked at the Omega as he walked by as if he knew the inner turmoil Castiel was suffering. 

"Class, I have your pop test results today. I have to say, it was rather disappointing. The questions weren't overly hard and I feel as a lot of you didn't put in the effort required. I'll hand back all your tests now and we'll go through the questions one by one and discuss what the answers are."

The class groaned collectively causing Castiel to chuckle as he walked around handing out each person's test paper. When he got to the bottom of the pile, his cheeks reddened as he saw the scrunched and stained test paper that belonged to the young Alpha. With his head ducked, he shamefully put Dean's paper onto his desk and high tailed it back to the front of the class. 

Throughout the lesson, he didn't look at Dean once. He had become quite good at ignoring the Alpha's stare but today, he could feel those jade green eyes on him wherever he went. The Omega was sweating under his collar from what Dean's reaction was going to be and was dreading the end of class as he just knew the Alpha was going to linger and not head to the cafeteria for lunch like the rest of his classmates. 

Castiel's suspicions were confirmed as soon as the bell rang. The class filed out waving goodbye and wishing a good weekend to their teacher with Castiel returning the sentiment. As the last student filtered out, Castiel stood from his seat and closed the door behind them. He locked it and then moved back to his desk where he took a seat and just waited with his head bowed. 

Dean's heavy footfalls had Castiel's heart pounding hard in his chest and butterflies swirling in his stomach both from fear and excitement. Dean didn't say anything, not a word, but he didn't have to, Castiel could smell it all in the young Alpha's scent. 

"Look at me, Omega," Dean rumbled out. Castiel was helpless to obey, lifting his head at the demand and gasping at the arousal he saw in Dean's features. "You think this is a game? You think you can stand up the front of the room clearly aroused by my scent every day and then mark my paper with your spend and scent then ignore me?" 

"I-I," Castiel stuttered at a loss for words as to what to say. 

"You think you can just look like that, smell like that and get away with it?" Dean growled as he leant across Castiel's desk his scent assaulting Castiel's nostrils letting the Omega know he was angry but he was also aroused. 

"I've been sitting with a hard on all class and now you're going to help me out with it." Dean said before he rounded the desk and stood behind the Omega's chair, pulling his seat out so there was room for Castiel to stand. "Did you hear me, Omega? You're going to pleasure your Alpha. Now stand up and bend your ass over your desk and drop your pants."

Castiel whimpered at the order, feeling his body already starting to respond as the familiar feeling of slick coated his underwear. 

"I can smell you already," the Alpha whispered, "Can smell how wet you are, how much you want my knot. I knew you were easy but fuck, not this easy." the Alpha taunted. 

The Omega whined at the Alpha's words, another pulse of slick releasing from his body as he pulled his pants down and bent over the desk. The Alpha pressed himself against Castiel's back making the Omega shiver as he felt the impressive length of the Alpha press against his ass through the jeans of the younger boy. 

"Feel that Omega? Feel what you do to me?" Dean ground his hips against Castiel's as he spoke making Castiel grip hard at his desk, holding on to ground himself. "I'm going to breed you, fill you with my pups so everyone will know you're taken."

Castiel whimpered at the thought of being with pup, something he had always wanted but no Alpha to give it to him. He wasn't about to tell the teenager he was on heat suppressants that also provided birth control because that would shatter the illusion. 

"You want that don't you? Swollen with pup, tits full with milk. Fuck you'd look gorgeous walking around with my pup that no one knew who put there."

Castiel moaned loudly as yet another pulse of slick gushed from his ass, his body reacting to Dean's words, showing the Alpha how much he wanted that. 

Heated hands pushed up his dress shirt before there was the familiar sound of a zipper being pulled. It felt like it took an eternity for Dean to free himself but then the thick wet Alpha cock was pushing against his entrance, the Omega's slick lubricating the way for the Alpha to push in without any prep. 

"Holy fuck," Dean grunted as he bottomed out. "Fuck that's a tight ass."

"Alpha," Castiel whined, pushing his ass back to get the Alpha to move. His insides were on fire, his body screaming from the stretch to accommodate the Alpha but he loved the burn, craved it in fact, pushing himself in the minimal way he was allowed to fuck himself on the Alpha's dick. 

"Greedy ass, already filled with cock and still wanting more. You want my knot don't you?" When Castiel didn't answer and instead kept moving trying to fuck himself, he got a sharp slap to his rear. He hissed at the contact but still felt more slick pulse from his hole. "I asked you a question." the Alpha growled.

"Yes Alpha!" Castiel whined, "Please knot me. Need it so bad. It's all I want."

"I know it is," the Alpha taunted as he started to thrust at a powerful pace not giving the Omega any time to adjust.

“Oh,” Castiel moaned loud and long as Dean continued to pound into him, his thick cock pressing against his prostate over and over, sending sparks of pleasure through his body. He spread his legs wider, his feet leaving the floor as he spread as wide as he could while his hands griped the front edge of his desk for balance. The whole thing was moving with the erratic pace the Alpha had set and there was no doubt in the Omega’s mind that if someone were to walk past his classroom door right now, they would know exactly what was happening inside.

“Fuck you’re squeezing hard. You going to come before I even knot you? You that much of a slut that all you need is to be stuffed full?” Dean mocked only making Castiel squeeze down hard as he felt himself hurling closer and closer to the edge of orgasm. “Jesus, you are aren’t you? Fuck what a perfect Omega. Come on Omega, come on my cock like the little whore you are.”

Castiel’s eyes squeezed shut at the slurs, his body reacting as the Alpha taunted him with slick leaking profusely from his hole making a filthy squelching sound every time Dean thrust into him. The scratch of Dean’s jeans on his ass reminding him the young Alpha was still fully clothed, and the continued dirty talk from the Alpha had the Omega silently screaming out his orgasm. His body tensed as he came, his small Omega cock spurting helplessly between his stomach and the desk while his ass once more let out a gush of slick in preparation for a knot. However, much to Cas’ dismay, there was no knot to come. The Alpha instead pulled himself free and flipped the boneless Omega to his back.

“See this cock?” The Alpha questioned with his hand holding his impressive length made to look even bigger with the teen’s hands still quite small. “You’re going to get to know it a lot better. Every day I’m going to fuck you, either your ass or mouth, sometimes maybe both, and you’re going to be ready for me no matter when or where. You got that Omega?”

“Yes, Alpha” Castiel instantly replied licking his lips as he watched the Alpha stroke his cock which was covered in the Omega’s slick and leaking pre-cum profusely.

“Good, now get on your knees and make me come like a good Omega.”

And like a good Omega, he did.

**Author's Note:**

> Let me know your thoughts! 
> 
> My [tumblr](http://assbuttintheimpalafiction.tumblr.com/)


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